Sunday, October 18, 2009

The Left's war on science

One million malaria deaths a year is one million too many. As there is as yet no malaria vaccine, controlling mosquitoes is the best way to control the disease. An environmentally sensitive program of integrated pest management (IPM) is the ideal way to control mosquitoes. Such programs tend to be expensive, requiring as they do, close management and supervision. IPM is therefore beyond the means of poorer countries.

This leaves bed-nets and insecticides as the best means of malaria prevention for people who cannot afford mosquito-excluding insect screens on their home windows. Bed-nets have evolved into highly effective screens that not only exclude mosquitoes but also kill them, the latest versions remaining effective for three years or more. The main problem with bed-nets, as with all prophylactics, is that they must be used, and used correctly, in order to effectively do their job. Forget to deploy or properly close your net just once and you could be bitten and infected. Heat is also a problem: bed-nets greatly reduce air flow to sleepers making the hot nights in tropical climes even hotter. This discourages use in some of the areas with the biggest malaria problems. So whereas bed-nets are highly effective, they are not the perfect solution to the malaria problem.

The World Health Organisation (WHO) recommends 12 residual insecticides for indoor mosquito control. Of this dozen, DDT is unique in that it both kills and repels mosquitoes. DDT is not the perfect insecticide, however. The persistence that is one of DDT's greatest assets also makes it controversial – DDT degrades only slowly and some of its decay products, DDE for example, are believed to be biologically active. Thus the agricultural use of DDT, which saw millions of kilograms of the chemical broadcast into the environment, was inappropriate. When so used, insects develop resistance, sometimes very quickly, to an insecticide, and so it was with DDT. DDT remains effective against mosquitoes throughout much of Africa, however, the area where it is most needed. Modern indoor residual spraying (IRS) programs using DDT use only minute quantities of the insecticide and do not release significant quantities of DDT into the environment.

Many environmentalists oppose any use of DDT, however. Rachel Carson's book Silent Spring, the holy scripture of the environmental movement, is the ultimate source of this opposition. Saint Rachel rightly pointed out DDT's drawbacks (for agricultural use) but greatly overstated its toxicity. Environmentalists (overwhelmingly Leftists) refuse to accept that Carson erred in some of her pronouncements from on high, and savagely attack anyone even remotely critical of her writing.

Shortly prior to coming on board here at Asian Correspondent I wrote a short essay critical of Silent Spring for Australian journal Quadrant Online. The response from the political Left was swift and vicious but ungrounded in reality. Quadrant has now published my response to the ravings of those who refuse to acknowledge that Rachel Carson told some whopping great lies in making her case against DDT.